When formed in molds by expanding an extruded parison, hollow blow molded plastic articles such as containers or bottles usually have flash in at least one of the shoulder, neck and finish areas. The finish also has material which must be removed to provide an end face for sealing engagement with a closure or cap engageable with the neck of the article.
Various methods and apparatus have been previously used to remove the flash from an article and machine a face on the finish. In these methods, a separate apparatus or machine has been used to perform each step of removing the flash, removing material from the finish, forming a face on the finish, and inspecting the completed article. Conveyors move the articles from one machine to the next and separate transfer mechanisms associated with each machine pickup and load articles into each machine and unload articles from each machine.
In U.S. Pat. No. 4,614,018 there is disclosed a method and apparatus wherein hollow plastic articles to be trimmed are intermittently advanced through a plurality of generally circumferentially spaced stations by a turret carrying vacuum heads engaging the articles. To assure positive accurate location of the articles in each station, each vacuum head picks up and engages an article in a load station and continuously engages the same article throughout all successive stations unless the article is rejected and released prior to the unload station. Preferably, to facilitate processing runs of articles of different sizes, the articles are located and engaged relative to a bottom edge thereof. Preferably, to facilitate loading, unloading and processing of articles in the stations, each vacuum head can be moved to change the orientation of the axis of the article it is carrying from one station to another. When at least two articles could be processed at the same time in a station, the articles are laterally spaced apart when carried by each vacuum head assembly to facilitate processing them in the station. To facilitate changing the cycle time of the trimming apparatus, the turret and the loading and processing equipment in the various stations are all driven by a common variable speed drive. To facilitate processing runs of articles of different sizes, the location of the processing equipment in each station can be varied and adjusted with respect to the position of articles in the station engaged by the vacuum heads.
It has been known that when a simple conveyor is used, significant effort is needed to insure that the bottles are accurately located in each station prior to beginning the operation. The process of locating the bottle causes time loss and uses significant floor space. In addition, the conveyor speed must be relatively slow to prevent tipping of the bottles. The slow speed of the conveyor further limits the speed of the trimming system.
When a more complex apparatus with bottle holding nests is used, the location and speed problems are reduced and less floor space is needed. However, this type of conveyor requires a large number of bottles holding nests which require more investment and time for each job change. Such a method and apparatus are shown, for example, in U.S. Pat. No. 4,198,886.
Most bottles are designed to stand on a stable flat base. Because of this it is possible to handle most bottles on a simple conveyor without special tooling. However, empty plastic bottles with flash at the top are difficult to convey standing up because they are very unstable.
In application Ser. No. 07/757,391, filed Sep. 10, 1991, OI Docket No. 16549, now U.S. Pat. No. 5,167,316 issued Dec. 1, 1992, there is disclosed a method and apparatus for positioning and indexing molded hollow plastic articles for trimming molded hollow plastic articles having flash and a finish for a closure, wherein the articles are supported and moved in succession by vacuum conveyor which holds the articles in upright position and moves them past successive stations for deflashing, facing, inspection, rejection and unloading. The conveyor is a chain slat conveyor having longitudinally spaced vertical holes that communicate with a vacuum chamber over which the conveyor is trained. The conveyor is driven intermittently and moves the articles in succession past each of the stations. At the load station, the articles are oriented so that they are in proper alignment and relationship to the opening in the conveyor.
In each of the methods and apparatus for trimming and inspecting heretofore used, when it is desired to trim or inspect a hollow plastic container which has a neck at an angle to the vertical axis of the container so that the opening of the container has its axis at an angle to the longitudinal axis of the container, it has been common to have the tooling at the various stations of the trimming and inspecting apparatus be positioned at an angle in order to perform the work operation at each of the stations. Such operations include facing the open end of the container, leak checking, measuring the height of the finish on the neck, and label inspection. Such a method and apparatus is cumbersome in that it requires critical adjustment and further it is not possible to perform such operations at high speed.
In U.S. Pat. No. 5,121,587, an apparatus is described for applying closures on containers having a mouth which is inclined to the axis of the containers. Each container is gripped by jaws which grip the body of the container to rotate the container about an axis through the body of the container. However such an apparatus would not be accurate enough to hold the finish of the container for performing trimming, such as reaming, or inspection. It has been found that such containers is subject to distortion due to shrinkage.
Accordingly, among the objectives of the present invention are to provide a method and apparatus for tilting the containers at each station wherein a trimming or inspecting operation is to be performed which will function to orient the neck accurately in a vertical position; which has controlled acceleration and deceleration promoting positive container handling; wherein a single motion causes clamping and rotating; and wherein the apparatus can be readily adjusted to accommodate containers wherein the opening in the container ranges in angle from zero to 45.degree. so that the same apparatus can be adjusted to any angle of tilting or no tilting at all.
In accordance with the invention a method and apparatus for trimming and inspecting hollow plastic containers having a neck which has an opening that forms an angle with the vertical axis of the hollow container wherein as the hollow container is moved by a conveyor intermittently past a succession of stations of a trimming and inspection apparatus, the neck of the container is clamped and oriented so that the axis of the opening is vertical and the trimming or inspecting tooling is moved downwardly to engage and perform the trimming or inspecting. In a preferred form two containers are clamped and oriented.
Basically the apparatus comprises opposed clamping nests which clamp the neck of one or more containers as the container is moved intermittently to each station of the trimming and inspecting apparatus. The clamping nests are moved inwardly to clamp the neck of a container and are rotated to orient the neck of the container vertically. The movement of the clamping and rotating the nests is performed in a single continuous motion.